Method of preparation of a surfacing material from tar sands



Nov. 12, 1963 J. A. BICHARD 3,110,505

METHOD OF PREPARATION OF A SURFACING MATERIAL FROM TAR SANDS Filed May 2. 1961 M LL i 7 v s 2 i: 5\ r- I I I MECHANICAL TAR SANDS I 4 SEPARATION FIGURE 2 70-75F.: 5 MIN. MIXING: I009 OIL RECOVERY.

4 1m. RECOVERY SAND REMOVED, WT. ON TAR SANDS (DRY BASIS) N TOTAL WATER, WT. ON TAR SANDS (DRY sAsls) John A. Bichord INVENTOR PATENT ATTORNEY United States Patent 3,110,605 METHOD OF PREPARATION OF A SURFACING MATERIAL FROM TAR SANDS John A. Richard, Point Edward, Ontario, Canada, assignor to Esso Research and Engineering Company, a corporation of Delaware Filed May 2, 1961, Ser. No. 107,230

3 Claims. (Cl. 106281) The present invention is concerned with the preparation of surfacing material from tar sands, particularly from Athabaska tar sands. In accordance with the present invention, surfacing material is prepared from mined tar sands by a process which involves preparing the bitumenrich sand and sand substantially free of bitumen. A suitable mineral aggregate is then compacted with the bitumen-rich sand to produce a paving composition. A specific adaptation of the invention comprises an integrated process wherein, in an initial operation, the concentration of the bitumen is increased on a certain quantity of sand and'then this bitumen-rich sand is mixed with aggregate so as to produce the paving composition of the present invention.

In various areas of the world, tar sands exist which contain various types of hydrocarbons as, for example, the heavy deposits of Athabaska tar sands existing in Canada. These sands contain tremendous reserves of hydrocarbon constituents. For example, the oil in the sands may vary from about 5% to 21% by volume, generally in the range of about 12% by volume. The gravity of the oil ranges from about 6 to API, generally about 8 API. These sands may lie from about 200 to 300 feet below an overburden and the beds may range from about 100 to 400 feet thick. A typical oil recovered from the sands has an initial boiling point of about 300 F., 1.0% distilled to 430 F., 20.0% distilled to 650 F. and 50.0% distilled to 980 F. However, the recovery of hydrocarbons in the past has not been effective to any great extent due to the deficiencies in operating techniques for the recovery of these hydrocarbons. For example, a

relatively small amount of clay (from about 0% to 30%;

usually about 5%) in the sand greatly retards recovery of the oil utilizing conventional water techniques. Apparently the oil and the clay form skins whichenvelop small pockets of water often containing finely divided sand; then the enveloped pockets are distributed in water, thus forming a type of emulsion.

Numerous attempts have been made in the past to recover bitumen from the Athabaska tar sands in various manners. For example, it has been suggested that a solvent be added in order to reduce the viscosity of the bitumen, and in conjunction with water, to float the bitumen solvent mixture away from the sand. Although this technique achieves a good separation of clean sand, the addition of water results in problems with the formation of stable emulsions and sludges which have been very difli cult to separate. Thus, extensive supplementary processing has been required in order to avoid large oil losses;

It has also been suggested in the past that tar sands as they are mined be handled by a thermal process in order to recover the bitumen therefrom. However, this process has been uneconomical due to the large amount of heat which is lost due to the fact that the heat is imparted to the sand and cannot be effectively and efliciently recovered therefrom. It has been suggested for example that tar sands be handled in a direct fluid coking operation. However, as pointed out, this process is uneconomical due to the reasons given above. Also, any process that will effectively handle tar sands must have the ability to handle a very wide range of tar sand and compositions which occur even in an immediate location. Some processes as, for example, direct fluid coking are able to ice handle these widely different compositions and, in accordance with the present process, employing a two-phase operation wherein in an initial phase a substantially richened tar sand is produced and wherein in the second phase the enriched sand is for example mixed with satisfactory aggregate and other necessary additives in order to produce a pavigg composition, surprisingly effective results are secure The present invention may be readily understood by reference to the drawings illustrating the same. FIGURE 1 illustrates the integrated process of the present invention wherein two phases are illustrated. In the first phase of the operation, enriched sands are produced and in the second phase of the operation, the bitumen enriched sands are mixed with mineral aggregate and other additives to produce a paving composition. FIGURE 2 illustrates in some detail the criticality of utilizing the correct amount of water in the sand enrichment phase.

Referring specifically to FIGURE 1 illustrating an integrated process, tar sands as mined are introduced into a shearing-mixing stage or zone 3 of the sand separation phase by means of line 1. Water, at a temperature in the range from about 32 to about 111 F., is introduced by means of line 2 and mixed with the sands. This water may be introduced directly into the shearing-mixing zone 3. It is also to be understood that while only one mixing zone is illustrated, a plurality of shearing-mixing zones may be used and a plurality of injection points also utilized. As a specific example, the composition of the sand introduced into zone 3 comprises about 6% by weight connate water, 15% by weight of bitumen, about by weight of sand and about 5% clay. The clay content varies from about 0 to 30% in these sands but, in the specific example given, the clay comprises about 5% by weight of the total. The connate water content varies from about 1-12% The mixing operation in zone 3 is carried out under conditions wherein a shearing thrust is imparted to the sands being mixed with the added water. Under these conditions, substantially oil-free sands separate and the entire mixture is then passed into the second stage or zone of the sand separation phase which comprises a mechani cal separation zone 5. The sands are introduced into zone 5 by means of line 4.

This mechanical separation zone may comprise any suitable mechanical means for separating the substantially oil-free sands from the bitumen-rich sands. For example, the mixture introduced by means of line 4 may be sieved in order to separate the oil-free sand which oil-free sand is removed by means of line 11. The bitumen enriched sands in a plastic physical state are removed by means of line 6 and mixed in a second phase of the integrated process with mineral aggregate and other additives which are introduced by means of line 7.

The effectiveness of the present technique for the seperation of oil-free sand and the resulting production of bitumen enriched sand in the initial phase is illustrated in FIGURE 2. Referring specifically to FIGURE 2, the amount of water added is plotted along the abscissa and the amount of sand removed plotted along the ordinate. The connate water of the sand in FIGURE 2 is 6%. In all cases, the sand removed was substantially completely free from oil except when 400% water was added, at which point the removed sand contained 8% by weight of oil. Thus, the oil recovery at 400% Was only 92% as compared to at other water addition points. It is apparent from FIGURE 2 that when less than about 40% of water is added, no oil-free sand separated whereas when the water added exceeded about 40% by weight, the amount of sand removed rose rapidly to a point in excess of 60% bitumen-free sand. Thus, the remaining 40% of the sand contains the total amount of oil originally present 0n the total sand. As the water addition is increased, the amount of oil-free sand recovered decreases somewhat to about 50% and, as pointed out heretofore, at a 400% addition of Water about 50% of the sand was removed, which 50% of sand contained about 8% of the original oil. Thus, it is preferred that the amount of water added in the present process be in the range from about 40 to 400% of water, preferably in the range from about 50 to 150% of water by weight based upon the tar sands being processed and that the preferred temperature be about 50to 90 F.

With respect to the run wherein about 90% of water is added and the bitumen-free sand removal approximated 72% this run was made wherein the water was introduced at different times. Thus, the mineral aggregate introduced by means or" line 7 is bonded together by means of the bitumen present on the bitumen enriched tar sands, that is, each rock of the mineral aggregate is provided with a coating of bitumen. The coated mineral aggregate and the enriched tar sands are then compacted in order to produce the desired paving composition.

The finished bituminous pavement has a bearing strength sufiicient to carry the trafiic and also withstand cracking due to low stresses and thermo-stresses. The stresses placed in the mineral aggregate are relaxed through the flow of the bitumen present. The bitumen possesses suflicient adherence to hold the mineral aggregate without hardening for an appreciable time period. The composition of the present invention is suitable for application comprise dry mineral aggregates as, for example, crushed stone, crushed rock, sand, and soil which are bonded in a very effective manner by means of the bitumen on the bitumen enriched sands. The amount of aggregate used may vary appreciably as, for example, in the range from 20 to by weight based upon the total Weight of the dry enriched tarsands. The preferred amount of aggregate added is in the range from about 45-50% by weight, preferably about 5 0% by weight.

What is claimed is:

1. Improved integrated process for the production of a paving material from natural tar sands which comprises in a first phase adding about 40% .to 400% by weight based upon dry bitumen sands of water to said natural tar sands and subjecting the mixture whose temperature is maintained in the range from about 32 to about 111 F. to a'mixing-shearing action, thereafter subjecting said mixture in said first phase to a mechanical separation process whereby substantially oil-free sands separate from an enriched oil tar sands thereafter in a second phase adding mineral aggregate in an amount in the range from 20-80% by Weight based upon the total weight or" the dry unenriched sands to said enriched sands and mixing the same in order to produce a paving material.

2. Process as defined by claim 1 wherein the quantity of water added is in the range from about 40 to about 3. Process as defined by claim 1 wherein the connate water content of said natural tar sands is in therange from about 4 to 12%.

References (Iited in the file of this patent UNITED STATES PATENTS 918,628 Willis Apr. 20, 1909 1,763,204 Wallace June 10, 1930 3,041,267 Frame et al June 26, 1962 3,052,621 Clark Sept. 4, 1962 

1. IMPROVED INTEGRATED PROCESS FOR THE PRODUCTION OF A PAVING MATERIAL FROM NATURAL TAR SANDS WHICH COMRISES IN A FIRST PHASE ADDING ABOUT 40% TO 400% BY WEIGHT BASED UPON DRY BITUMEN SANDS OF WATER TO SAID NATURAL TAR SANDS AND SUBJECTING THE MIXTURE WHOSE TEMPERATURE IS MAINTAINED IN THE RANGE FROM ABOUT 32* TO ABOUT 111*F. TO A MIXING-SHEARING ACTION, THEREAFTER SUBJECTING SAID MIXTURE IN SAID FIRST KPHASE TO A MECHANICAL SEPARATION KPROCESS WHEREBY SUBSTANTIALLY OIL-FREE SANDS SEPARATE FROM AN ENRICHED OIL TAR SANDS THEREAFTER IN A SECOND PHASE ADDING MINERAL AGGREGATE IN AN AMOUNT IN THE RANGE FROM 20-80% BY WEIGHT BASED UPON THE TOTAL WEIGHT OF THE DRY UNENRICHED SANDS TO SAID ENRICHED SANDS AND MIXING THE SAME IN ORDER TO PRODUCE A PAVING MATERIAL. 